The present invention relates generally to apparatus for the direct conversion of the energy of radioactive decay products to electrical energy and, more particularly, to the utilization of an alpha source to sustain and amplify oscillations in an LC oscillator circuit.
A growing need exists today for small, compact, reliable, lightweight and self-contained rugged power supplies to provide electrical power in such applications as electric automobiles, homes, industrial, agricultural, recreational, remote monitoring systems and satellites. The majority of today's satellites are powered by solar cells and conventional chemical batteries and require only a small amount of power to operate. Radar, advanced communications satellites and, especially, high-technology weapons platforms will require much larger power sources than today's space power systems can deliver. For the very high power applications, nuclear reactors appear to be the answer. However, for the intermediate power range, 10 to 100 kilowatts (kw), the nuclear reactor presents formidable technical problems. Given today's efficiencies, it would require many acres of solar panels to provide 100 kw. Similarly, enough chemical fuel to provide 100 kw for any significant period of time would be too heavy and bulky for practical use.
Heretofore, there have been known several methods for conversion of radioactive energy released during the decay of natural radioactive elements into electrical energy. A grapefruit-sized radioisotope thermo-electric generator that utilized the heat produced from alpha particles emmitted as plutonium-238 decays was developed during the early 1950's. However, the power output was limited to a few hundred watts. Other methods converting the energy of radioactive decay directly into electrical energy are disclosed in U.S. Pat. Nos. 3,290,522; 3,409,820; and 3,939,366.
U.S. Pat. No. 3,290,522 entitled "Nuclear Emission Electrical Generator" issued to Robert Ginell on Dec. 6, 1966, discloses apparatus which provides electrical power by modulating the density of a cloud of charged particles confined within an enclosed space by a magnetic field. A radioactive material is positioned at the center of an enclosing hollow sphere having its inner surface coated with silver. The sphere is centrally positioned between the poles of a permanent magnet. The variation in the density of the cloud of charged particles causes a variation in the magnetic field created by the cloud. This variation in the magnetic field cuts an electrically conductive means to create an electrical potential and current therein. The density of the cloud of charged particles may be varied by applying a periodically varying electro-static or electro-magnetic field to the confined cloud of charged particles. The electrical energy is derived from the kinetic energy imparted to the charged particles (decay products) on the occurrence of a spontaneous disintegration event during the decay of the radioactive material. However, with this system, the conversion efficiency is very low and the amount of electrical power provided too small for most applications.
U.S. Pat. No. 3,409,820 entitled "Electric Power Appartus" issued to James O. Burke on Nov. 5, 1968, discloses an amplification of an electric current by the conduction of electric current through a radioactive material. While providing some current amplification, the system requires an external power source, such as a conventional battery, and thus, cannot provide sufficient power for most applications.
U.S. Pat. No. 3,939,366 entitled "Method of Converting Radioactive Energy to Electric Energy and Device for Performing the Same" issued to Yasuro Ato et al. on Feb. 17, 1976, discloses an apparatus in which radioactive energy is converted to electric energy by irradiating a semiconductor material with radioactive decay products to produce a number of electron-hole pairs in the material. A magnetic field is applied across the semiconductor material in a direction perpendicular to the direction of diffusion of the electron-hole pairs and to the direction of the applied magnetic field thus collecting the electrons and the holes at electrodes provided on the respective end faces of the semiconductor material to produce an electric potential across the semiconductor material. While the conversion efficiency of the system disclosed by Ato et al. is considerally higher than that disclosed by either Burke or Ginell, the power output of the system is not great enough for applications such as electric automobiles or satellites.